PATHETIC!!!!

I took out a Cell C contract in May this year with Cell C. Last month I receive a statement stating that I have to pay R269 for DATA I DID NOT RECIEVE. Firstly this was not on the contract that I signed with Cell C. You cannot just add money for no reason. I then phoned Cell C to sort this out. They admitted numerous times that they did indeed make a mistake and that they overcharged me. So... I told them I will pay the money that I know I owe.. Hence the contract fee and extra for calls made. No problem. They said I will have to pay the full amount and next month it will be deducted. I declined this as I have a strict budget and cant afford to pay MORE THAN I SHOULD!!!!. This was not my mistake in the first place. Now I keep sending emails to Cell C to sort it out and I hear nothing from them. I keep getting sms's saying that my account is in arrears and if I don't pay I will get a bad credit score. THIS IS PATHETIC. THIS WAS NOT MY FAULT OR MISTAKE IN THE FIRST PLACE. NEVER IN MY LIFE HAVE A COME ACROSS THIS. And no one bothers to phone me back with any information or feedback.